This invention relates to the fabrication of optical fibers.
The common method of fabricating an optical fiber begins with a quartz substrate tube. A chemical vapor deposition process is used to deposit one or more glass cladding layers and then a glass core layer on the interior surface of the substrate tube. The tube is then radially collapsed by a heating process to form a preform from which the fiber is drawn.
No provision is made, however, for applying photolithographic or other patterning techniques to treat selected zones of the cladding or core layers. In particular, these layers as deposited are continuous in both circumferential and axial directions; they are not patterned to effect different fiber geometrical shapes or optical properties. Nor does their composition vary significantly in the circumferential direction.